What Hanafi premise is supported by “li-yuṭahhirakum” in the tayammum discussion?

Explicit and Allusive Wording: Clarity, Intention and Legal Effect

• Tayammum is lawful only for the funeral prayer
• Tayammum grants permission to pray but not purification
• Tayammum establishes ritual purity
• Tayammum can be valid only after the prayer time begins